Escapement drive for motion picture films



Nov. 4, 1958 A. JANSSON ,8

ESCAPEMENT DRIVE FOR MOTION PICTURE FILMS Filed June 25, 1956 I N V EN TOR. 04 V10 Jn/vsso/s/ 7 WWM a r roPA/e. 77

United :States Patent Ofiice 2,858,704 Patented Nov. 4, 1958 Arvid Jansson, Pittsburgh, Pa. Application June 25, 1956, Serial No. 593,637

3 Claims. c1. 74 s4 My invention relates to intermittent driving mechanisms for motion picture films and the like, wherein movement of the film has to be intermittent, the film becoming temporarily stationary when each frame thereof comes opposite the lens.

While Geneva drives have been employed heretofore for this purpose, such drives usually utilize one-half of each cycle of movement for a pause period and one-half of the cycle for movement.

My invention has for one of its objects the provision of an escapement mechanism and drive that will permit of more rapid movement of the film between exposures, thereby increasing the rapidity of film travel, without reducing the exposure periods, or to thereby increase the exposure periods, if desired.

Another object of my invention is to provide driving apparatus of such form that it can be incorporated into present film machines in connection with certain standard parts of such drives.

As shown in the accompanying drawing,

Figure 1 is a sectional view through my driving mechanism in association with film moving sprockets;

Fig. 2 is an end elevational view of certain of the mechanism of Fig. 1;

Fig. 3 is a longitudinal sectional view on an enlarged scale, through a portion of the transmission mechanism of Fig. 1;

Fig. 4 is an end view of the overload release clutch of Fig. 3;

Fig. 5 is an enlarged view of a portion of the escapement mechanism of Figs. 1 and 2, and

Fig. 6 is an end view of the escapement wheel of Fig. 5.

The usual film-driving sprockets are indicated by the numeral Sand are pinned to a shaft 9 that, at its inner end, has secured thereto or formed integrally therewith a star wheel 10.

A driving gear 11 and a fly wheel 12 are connected to a tubular driving shaft 13 by a set screw 14, the gear wheel 11 being driven from an electric motor. At its inner end, the tubular driving shaft 13 rotates in a bearing 15 and has secured thereto or formed thereon a pinion 16 which meshes with a gear wheel 17 fixed to a timer shaft 18 to which is also fixed a pinion 19 that meshes with a gear Wheel 20. There is a 4 to 1 ratio between the gears 16 and 20. The gear wheel 20 is thus constantly driven by the pinion 19. Gear wheel 20 is non-rotatably mounted on hub 21, the inner end of which is rotatably journaled within the axial tubular portion of driving shaft 13. A normal peripheral extension of a spring 22 is fixed said inner hub 21, by means of which, gear wheel 20, acting through 22, has driving connection with a clutch ring 23, to which an opposed normal peripheral extension of spring 22 is fixed; that, thereby, clutch ring 23 through ball clutch members 24 drives a second clutch ring 25. The ring 25, through a spring 26, has driving connection with collar 27 that is secured to a driven shaft 28. Spring 26, having extensions similar to spring 22, is fixed thereby to clutch ring 25 and collar 2 27, respectively. The clutch rings 23' and 25 are rotatably mounted on the shaft 28, and the springs 22 and 26 exert endwise thrusts against the clutch rings to thus produce a slip-clutch connection between the gear wheel 20 and the shaft 28.

The shaft 28 has an enlargement 29 at its inner end, and a tongue 30 that extends into one of the slots 32 of the star wheel 10 which serves to drive the shaft 9 that carries the sprockets 8. Anti-friction balls 31 are inter posed between the'members 21 and 29.

The shaft 18 also carries a spiral pinion 33 that drives a spiral gear 34 upon whose shaft 35 an escapement wheel or disc 36 is mounted. The escapement disc has openings 37 therein and is driven about an axis that is at right angles to the shaft 9, so as to intermittently hold the sprockets 8 against rotation. These sprockets are permitted to turn one-fourth of a revolution each time that the disc 20 makes a one-half revolution. That is, during each revolution of the disc 36, one of the openings 37 will come opposite a projection on the star Wheel 10, allowing it to turn one-fourth revolution, at which time a succeeding arm of the star will engage an unnotched portion of the escapement wheel, it being understood that the sprocket shaft 9 is under constant tension by reason of the driving connection through the springs 22 and 26 and their clutch members 23 and 25. It will thus be seen that each movement of the film is by a sort of snap action and therefore effected quickly, while the dwell of the film frame at the lens opening will endure for the period of time which it takes the disc 36 to make a one-half revolution.

The slip clutch 23-2425 prevent overstraining of the mechanism, although the gear wheel 11 is being constantly driven. That is, when the escapement holds the star wheel against movement, torsional tension'will be built up in the spring 22 until such time as the force is sufficient to overcome the axial pressure of the spring 26 and therefore cause it to displace the balls and the disc 25, so that the gear wheel 20 will be rotated independently of the shaft 28, thus avoidingstrain on the star wheel and the escapement disc.

During this time however, the spiral gears 3334 will be rotating andv the escapement disc moved to permit another one-fourth revolution of the star wheel and an advance of the film for a distance of one frame under torsional stress of the springs. The movement will be quite rapid because of the torsional stress on the springs 22 and 26.

It will be understood that the friction in the ball clutch at 24 will be sufiicient to transmit torsional stress from the springs 22 and 26, with enough force to rotate the shaft 28 through one step of star wheel movement.

I claim as my invention:

1. The combination with a rotatable driving shaft, a driven shaft, an escapement for the driving shaft adapted to periodically restrain said driven shaft from rotation, an escapement driving means drivably connected between said driving shaft and said escapement, a rotatable member mounted on and rotatable with respect to said driven shaft, said rotatable member being drivably connected to said escapement driving means, a driving connection between said rotatable member and the driven shaft that comprises a coil spring which has one end fixed to said rotatable member, a second coil spring which has one end fixed to the driven shaft, clutch rings respectively fixed to the other ends of said coil springs, said clutch rings being in proximity to each other and both rotatable relative to the driving shaft and the driven shaft, and slip clutch means interposed between the clutch rings, the clutch rings being yieldably held in driving engagement with each other by endwise pressure of the springs during rotation of the driving shaft and while rotation of the driven shaft is being restrained by the escapement, the springs being placed under torsional stress that will overcome the clutching action of the clutch rings during rotation of the driving shaft, the clutching force of the clutch rings being sufficient to transmit driving movement from the springs to the driven shaft when the driven shaft is released by the escapement.

2. A combination as recited in claim 1, wherein the driving shaft, the driven shaft, the clutch rings and rotatable member are co-axial with one another.

7 3. A combination as recited in claim 1, wherein the driving shaft has a tubular body portion that surrounds the driven shaft, the coil springs and the clutch rings,

'4 and the driven shaft projects from one end of the tubular body.

References Cited in the file of this patent UNITED STATES PATENTS 359,841 Browne Mar. 22, 1887 369,004 Hubbard Aug. 30, 1887 560,424 Petit May 19, .1896 966,090 Hamacek Aug. 2, 1910 1,007,962 Nolan Nov. 7, 1911 1,104,873 Butcher July 28, 1914 1,274,749 Neill Aug. 6, 1918 1,378,153 Trotter May 17, 1921 

